the 4200-002 is designed for 4-way mounting

and Tempstar brands

As a critical motor starting relay

What causes a collector box to fail

Can this timer be used for 3-way switching applications

Carrier HK42FZ039 Control Board R-134A the 4200-002 is designed forThe Carrier HK42FZ039 Control Board is a critical OEM replacement circuit board engineered for high performance management of residential HVAC furnace and air handler systems. This gas furnace control board serves as the central processing unit, regulating ignition sequences, blower motor speeds, and safety limit circuits. Built to genuine Carrier HVAC parts standards, the HK42FZ039 ensures precise timing for draft inducer motors and gas valve